As described in Patent Literature 1, a device having a configuration, in which a heating chamber is accommodated in a heat insulating and hot water storing chamber, and an electric heater is accommodated inside the heating chamber, has been known as a washer fluid heating device. A washer fluid is heated by the electric heater inside the heating chamber, and then supplied to a washer nozzle by driving of a washer pump, and sprayed from the washer nozzle. In such a heating device, when the washer fluid in the heating chamber decreases, there is concern that so-called no-water burning may occur. In the device described in Patent Literature 1, the washer fluid in the heat insulating and hot water storing chamber may be allowed to flow into the heating chamber when an outflow passage of the washer fluid is open at the upper portion of the heating chamber. In this way, the heating chamber is prevented from being empty, and no-water burning is prevented.
Meanwhile, as described in Patent Literature 2, a device in which a heater is provided in a tank of an electric water heater has been known. In this device, no-water burning is prevented by suspending heating when a temperature difference between a first thermosensor attached to a flange face of the heater and a second thermosensor attached to an external wall of the tank is greater than or equal to a set value.